Amplifying valve of the progressive wave type



June 13, 1950 w. KLEEN ET AL 2,511,407

AMPLIFYING V'ALVE OF THE PROGRESSIVE WAVE TYPE Filed Dec. 27, 1947 2 Sheets-Sheet 1 ATTORNEY June 13, 1950 w. KLEEN ET AL 2,511,407

AMPLIFYING VALVE OF THE PROGRESSIVE WAVE TYPE Filed Dec. 27, 1947 2 Sheets-Sheet 2 INVENTORS my? NEH /(1 5,

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A TIORIVE r Patented June 13, 1950 UNITED STATES PATENT OFFICE F THEPROGRE SS I VE WAVE TYPE Werner- Kleen, Osk'ar Dohler, a'fia- Harry Huber,

Paris, France, assignors toCompag'nie G e'n'erale de Telegraphic Sans Fil, a; corporation of France Application'DecernberM, 1947; Serial No; 794,164 In France January 9; 1947 6 Claims. (Cl. 315'39 The present invention relates to an amplifying valve, in which the amplification is obtained by the interaction, in a duct between a beam of electrons and a progressive. electro-magnetic wave. The known valves of this type have the disadvantage of a substantial length, involving dilficultiesi-in focus'sing-the beam of electrons-,and it is the objectof-the present: invention to obviate:

this disadvantage.

Figures 1 and Zrepresent respectively in transverse and axial section a: preferredform of the invention;

Fig, 3 represents in perspective and very diagrammatically. a: modified form of the invention of which Figs; 4a;.4'b and 5 show details of. construction;

In'Figs. 1- and 2; reierenc'e characters I and 2 represent two circular conductors between which a wave can propagate along the periphery of the--conductors; k" the cathode,.e the input coupling; and s the output coupling. The electrode l is insulated from the-mass of the tube comprising the electrode 2 by insulatingpie'cesfl.

Perpendicularly. to the plane of Fig. 1 there is produced, by means of the-poles'NS visible in- Fig. 2, a magnetic field whose induction has a constantfvalue'B; Between the electrodes l and 2 a direct voltage is applied through the terminals 4 whichproduces between the electrodes l and 2 an electric field in the radial direction which does not change in'time. The electrons leaving the cathode k move in a peripheral direction with a circular velocity E0 denoting-metals of the radial electric" field at a gi'v'e'n' distance'froiflthe conductor l.

h In ordrthatthe exchange of energy between the electrons and the electro-magnetic wave may be in the direction that is favorable for the utilization of the tube for amplification, the phase velocity Vp of the wave should be approximately equal to V. Normally the phase velocity of an electro-magnetic wave in a guide or duct is distinctly greater than that of the electrons for reasonable values of E0 and of B, the value of B, for a given value of E0 being necessarily greater than a critical value which is defined by the fact that below this value the electronic trajectories would not be circular in the direction of the periphery. In order to equalize V and Vp, the phase velocity of the wave that is being propagated between the conductors I and 2 should be diminished.

This diminution is produced by inter'posing longitudinal inductances in the walls of the electrode 2, or of the electrode I, or of both at the same' time. These inductances are produced for example by slits uniformly distributed in the walls, which constrain the surface current to make detours, that is to say, the action may be" expressed in the equivalent diagram by the existence of longitudinal inductances.

In order that the tube may operate asaniamplifying valve it is necessary to avoid auto-excitation. Iii-order to attain this aim, according tothe invention three conditions are essential:

(a The wave starting from the input should be able topr'opagate itself in one direction only';

(1)) The wave should traverse the path between the input e' and the output s once only;-

(c) The rotation of the electrons emitted by the cathode around the central electrode I should never exceed 360.

These conditions, which are very important for the operation of the tube, are fulfilled for the wave and for the electrons by closing the tube at p, behind the output s. This is-shown diagrammatically in Fig. 1.

As regardsthe cathode, it is possibleto utilize a thin filament extending in a direction p'a'rallel to the axis of the system. The cathode k: is sub jected iii-this device to a continuous voltage-in relation to the electrodes l and 2, which is equal or approximately equal to the potential of the point 7c between the electrodes l and 2 inthe absence of the cathode. This voltage is tapped on a potentiometer 5 inserted between the terminals 4, the tapping point being connected to the cathodic conductor 6; I

It-should be observed that since the path of the electrons is interrupted at p, theycannot cause a supplementary heatingof the cathode, as in ordinary magnetrons, which also constitute another advantage of the invention.

The arrangement illustrated in Figs. 1 and 2 somewhat resembles that of the usual magnetrons having a large number of circuits. It differs from the latter however in some essential points, particularly the following:

(1) The cathode of the proposed valve is not located in the axis of the system; (2) the closure of the valve at the position 10 of the tube is absolutely essential for the operation of the tube as an amplifier; (3) the constant magnetic field in this tube should be of definite sign, as a reversal of the magnetic field would prevent the tube from operating; whereas for the ordinary magnetron, reversal of the magnetic field has no influence on the operation of the tube.

Figs. 1 and 2 represent the diagram of a tube according to the invention in which the velocity of propagation of the Wave is diminished by slits ,f uniformly distributed in the walls. It is evident that the tube may be provided with devices of any sort which will diminish the velocity of propagation of the wave.

Fig. 3 shows by way of example another form of tube. In this figure the same parts bear the same references as in Fig. 1. In this case the wave is propagated along a Lecher system L, which is curved into the form of a circle. One or both of the conductors of the Lecher system are represented by very flat helices h, with rather close turns, as shown in transverse view in Fig. 4a and in plan in Fig. 419, or by wires of sinuous form as shown in perspective in Fig. 5, which leads to an increase of the longitudinal inductances by the formation of a winding path.

Compared with known tubes, the valve according to the invention has the following advantage, in addition to that of very small dimensions: in the known tubes the electrons which give up energy to the wave lose velocity. The velocity being diminished, the electrons cannot move with the velocity of the wave until the end of their discharge path, which diminishes the interaction between the electrons and the Wave, and consequently diminishes the emciency and the advantage of the tube. In the proposed tube the electrons always possess the same velocity, because the transfer of energy to the wave is compensated for by the removal of energy by the radial electric field E0, in such a way that the circular velocity of the electrons, that is to say, the velocity in the direction of the wave, is always given by the relation What we claim is:

1. In an electronic amplifier comprising an emissive cathode, means for establishing a substantially time-constant magnetic field, said cathode being located within said field the lines of force of the field, in a given direction, being substantially paralle1 to the surface of the said cathode, and an interaction duct, the combination which comprises, two substantially parallel conductors having their surfaces parallel to the lines of force of the magnetic field, the cathode being located between the two conductors, adjacent one of the ends thereof, the surface of the cathode being substantially parallel to the conductors, a terminal connection to the cathode enabling the surface thereof to be brought to a potential differing from that of the conductors, terminal connections to the conductors thereby to produce therebetween an electrical potential giving rise to a substantially time-constant electrostatic field substantially perpendicular to 4 the said time-constant magnetic field, at least one of the conductors including elements forming an electrical delay line, thereby to produce a radio-frequency field having an electrical com= ponent perpendicular to the crossed substantially time-constant electro-static and magnetic fields, said elements having the characteristics of longitudinal inductances inserted in a Lecher line, and being so dimensioned that the phase propagation velocity along the delay line is less than in space and substantially equal to the velocity of electrons in the duct, the said electron velocity being determined by the ratio of the intensities of the electric and magnetic fields, the said conductors, from the point of view of radio-frequency waves travelling over the surface thereof, having input and output extremities separated from each other to enable mutual decoupling thereof and prevent feed-back oscillations, the said extremities being provided with means for coupling to outside circuits for exciting an electromagnetic wave in the radio frequency input termina1 and for collecting amplified energy at the ratio-frequency output terminal.

2. A device as in claim 1, wherein the two conductors of the duct are curved along the arc of a circle concentrically to each other, decoupling means being located between said radio-frequency input and output terminals and comprising a metallic separation wall inserted in the circular space between said terminals.

3. A device as in claim 1, wherein at least one of the conductors of the duct acting as a delay line is wound in the form of a flat helix.

4. A device as in claim 1, wherein at least one of the conductors includes slits normal to the direction of the duct, the structure of the said conductor providing gaps wherein is developed the radio-frequency field acting on the electrons.

5. A device as in claim 1 wherein at least one of the conductors follows a winding path.

6. A device as in claim 1 wherein at least one of the conductors is provided with vanes defining gaps wherein is developed a ratio-frequency field acting on the electrons.

WERNER KLEEN. OSKAR DGHLER. HARRY HUBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,064,469 I-Iaeff Dec. 15, 1936 2,367,295 Llewellyn Jan. 16, 1945 2,409,038 Hansell Oct. 8, 1946 2,444,242 Blewett June 29, 1948 

